Resources

CodePen is a social development environment for front-end designers and developers.
Stop wasting time setting up a development environment. Repl.it gives you an instant IDE to learn, build, collaborate, and host all in one place.
The MDN Web Docs site provides information about Open Web technologies including HTML, CSS, and APIs for both Web sites and progressive web apps. It also has some developer-oriented documentation for Mozilla products, such as Firefox Developer Tools.
jQuery is a fast, small, and feature-rich JavaScript library. It makes things like HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a multitude of browsers.
A JavaScript library for building user interfaces.